1. Field of the Invention
The present invention relates to disk drive testing, and more particularly, to analyzing a magnetic media surface in a disk drive for damage caused by rough handling.
2. Description of the Prior Art
A damaged disk drive may appear normal for a period of time due to the drive""s internal error correction processes. However, once uncorrectable errors begin to appear in data due to media surface damage caused by rough handing, significant irreversible data loss may have already occurred and catastrophic data loss may be imminent. Further, disk drive manufacturers commonly provide warranty coverage that excludes disk drive failure due to rough handling or similar mistreatment. Much of the costs to the manufacturer associated with processing a disk drive exhibiting a failure are incurred by returning the drive back to the manufacturer for testing to determine whether the failure is covered by the warranty.
Accordingly, there exists a need for disk drive analysis techniques for analyzing a magnetic media surface for indications of damage caused by rough handling while the drive is installed in a host computer. The present invention satisfies theses needs.
The present invention may be embodied in a method, implemented in a disk drive, for analyzing a magnetic media surface for indications of an impact of a read/write head on the surface. In the method, a media surface is scanned to detect errors indicative of media defects. Location information is recorded for each detected error. Defect clusters are identified based on the location information. At least one confidence factor is generated based on a comparison between the defect clusters and a representation of the physical dimensions of the head. Whether the confidence factor(s) indicates an impact between the head and the media surface is determined.
In more detailed features of the invention, data sectors on a portion of the media surface surrounding a suspect location may be mapped into meta-sectors and meta-cylinders that are related to the physical position of the data sectors on the media surface. The location information for each data sector of the surrounding portion of the media surface having a detected error may be recorded by a defect count in a bin associated with the meta-sector and meta-cylinder into which the data sector having the indicative error is mapped. Also, the representation of the physical dimensions of the head may be generated by converting the physical dimensions of the head into meta-physical dimensions related to the mapping of the data sectors into the meta-sectors and meta-cylinders. The meta-sectors may comprise 64 meta-sectors and the meta-cylinders may comprise 32 meta-cylinders. Further, the comparison between the defect clusters and a representation of the physical dimensions of the head may include identifying defect clusters associated with corners of the head. Finally, a bit error threshold for detecting data sectors having errors indicative of media defects may be lower than a bit-error threshold used by the disk drive for placing data sectors on a defect list for preventing data storage in the listed data sectors.
In another embodiment of the invention, the disk drive may include a plurality of media surfaces that are scanned to detect errors indicative of media defects. A confidence factor is generated for each defect cluster. The confidence factors of defect clusters at corresponding positions on the plurality of media surfaces are combined to generate a combined confidence factor. Whether the combined confidence factor indicates impacts between the plurality of heads and the respective media surfaces is determined.